OFBizian: Apache Isis

Here, I want to briefly talk about two open source projects I love playing with.

OptaPlanner is a constraint solver. It optimises business resource planning use cases, such as Vehicle Routing, Employee Rostering, Cloud Optimization, Task Assignment, Job Scheduling, Bin Packing and many more that every companies face daily. It can help squeeze the last bit of optimisation in your planning challenges and improve service quality and reduce costs. It is a lightweight, embeddable planning engine, consisting from a single .jar file.

Apache Isis on the other hand is a framework for rapidly developing domain-driven apps in Java. Write your business logic in entities, domain services or view models, and the framework dynamically generates a representation of that domain model as a webapp or a rich hypermedia REST API. It is a full-stack application where once you write your domain layer, you get the persistence and presentation layer for free. It let's you very quickly to developer and iterate over the domain model.

Both of these projects allow developers create user focused applications and solve read world problems. And both of them are centred around domain-driven design approach and fit nicely into Java development model using annotations. Last year, around this time, I decide to combine them and created a pet project called RotaBuilder. I migrated the existing Java Swing based Employee Rostering application from OptaPlanner examples to Apache Isis and turn it into a containerized web application. Below is a screenshot of an employee view.

An employee view created in Apache Isis and OptaPlanner

The application is on github and offers the following features:

Manage employees
Manage skills
Manage days on/off requests
Manage shift on/off requests
Manage contracts
Manage shifts
Create automatic employee-shift assignments

It is far from complete, but I probably will not have time to work on it in a near future. I decide to push on public github in case anybody wants to learn these projects by developing an employee rostering application. For me, the best way for learning something has been doing it.

Local Build and Run with Maven

It is straightforward to locally build and run with maven.

mvn clean install -DskipTests=true
cd webapp
mvn jetty:run

then go to http://localhost:8080/

Run with Docker

It is also available as Docker image

docker run -p 8080:8080 bibryam/rotabuilder

Live Demo on Red Hat OpenShift

See live demo (if it is) running at http://rotabuilder.com

TL;DR This post talks about a SEMAT pet project I created using Apache Isis and deployed to OpenShift Online here http://semat.ofbizian.com

Apache Isis

As a Java developer who is working primarily on backend systems, I ~~hate~~ do not enjoy creating user interfaces and dealing with Javascript. Luckily, there are Java projects such as JSF (grrr), Apache Wicket, Vaadin that can help avoid Javascript altogether and still create functional user interfaces. But even with these projects, the developer has to think about and actively create the user interface from Java code. That is similar to writing your own SQL statements in the age of ORMs such as Hibernate - an activity we do only when OOTB ORM is not good enough for the use case. And that is exactly where Apache Isis fits in: given a domain model and mapping annotations, it generates the complete user interface at runtime. In a sense, Apache Isis is a OUIM (Object/User Interface Mapping) framework for Java.
There is much more to Apache Isis than only creating user interfaces, it is a full stack rapid application development framework focused on domain driven design. But rather than talking about it, let's see a complete application created with Apache Isis.

SEMAT Essence Kernel

To learn Apache Isis, I decided to implement the SEMAT model and deploy it to OpenShift Online asa Docker container. Simply said, SEMAT (Software Engineering Method and Theory) Essence Kernel is a OMG Standard that helps define among other things a framework for describing the state of software projects from multiple perspectives (called alphas).

SEMAT Alpa States

The idea is, that every project can be described in a generic way using the following seven alphas:
Stakeholders, Opportunity, Requirements, Software System, Work, Team, Way-of-Working. And each Alpha can be in one or multiple states, for example, the Stakeholders can be: Recognized, Represented, Involved, In Agreement, Satisfied, etc. In addition, each state has certain items to be satisfied before an Alpha can be transitioned to that state.

Stakeholders Alpha's States

As you can see, this is a pretty simple domain model with a state machine logic behid it.

The Showcase Application

Enough said, to see how much Java I had to write for this application, check the dom module of the project on github. All of the other skeleton code is generated through a maven plugin and no user interface code is required. And here is a screenshot of the Project domain entity screen rendering:

Project view as Apache Wicket screen

In addition to generating a user interface, Apache Isis will generate also a REST API using the same domain model. How cool is that.

SEMAT REST API generated from domain model

And the beauty of all this is, that generating UI allows you quickly to iterate over the domain model, show it to the business owners to get feedback and contonue evolving the model.

Some of the SEMAT Application Features implemented/enabled

Multi tenancy
Manage multiple projects per tenant
Manage project Alpha states
Custom Essence Alpha state list per tenancy
Custom Essence Checklist items per tenancy
Alpha state spider/radar diagram
Automatic Apache Wicket based UI generation from domain model
Automatic REST API generation from the same domain model
Self Signup/Registration
Auditing user actions
Session logging
Internationalization
Breadcrumb trail
Bookmarks

Build and Run

Check the readme for full details, but you can build and run the application locally or on OpenShift to try it out.

mvn clean install
cd webapp
mvn jetty:run

or

mvn clean install
docker build --rm -t bibryam/semat .
docker run -p 8080:8080 bibryam/semat

Then go to http://localhost:8080/ and login: user/user

Deploy to OpenShift

Once you have got an OpenShift running either locally or online, and have a oc client installed, then you can deploy the already build semat docker image with the following commands:

oc new-project semat
oc new-app bibryam/semat:latest -e CATALINA_OPTS=“-Xmx300m”
oc expose service semat

If you do not trust docker images build by others (you should not!) then you can build your own docker image as shown above with options 2 and 3 and push it your own docker registry and run the application from it:

oc new-app your_name/semat:latest -e CATALINA_OPTS=“-Xmx300m”

Alternatively, you could avoid installing and running docker all together, and have the source code and the docker image build on OpenShift. That is called OpenShift Source-to-Image approach. You can do this from OpenShift UI by using for example "Red Hat JBoss Web Server 3.1 Tomcat 8 1.0" template and pointing to the SEMAT github repo. Or use the template provided in the project itself:

oc create -f semat-openshift-template.json
oc process semat

Using source to image approach allows setting up github webhooks, have a Red Hat base image, have jolokia added, Java memory configurations done, etc.

Live demo on OpenShift

See try out the application, check live demo running on a OpenShift Online http://semat.ofbizian.com

In summary, if you have a domain model that changes often, and the agility in changing the domain logic is more important than how the user user interface looks like, check out Apache Isis. It is an incredible productive and fast business application development framework.
Follow me @bibryam for future blog posts on related topics.